1. Field of the Invention
The present invention relates to a light source unit, a liquid crystal display (“LCD”) having the same, and a method thereof. More particularly, the present invention relates to a light source unit which can minimize current differences between a plurality of light emitting diodes (“LEDs”), an LCD having the light source unit, and a method of minimizing current differences between LEDs.
2. Description of the Related Art
Liquid crystal displays (“LCDs”) have a structure in which a liquid crystal layer is interposed between a common electrode display panel on which a reference electrode and color filters are formed and a thin film transistor (“TFT”) substrate on which switching devices and pixel electrodes are formed. LCDs generate an electric field by applying different electrical potentials to pixel and reference electrodes, change the arrangement of liquid crystal molecules using the electric field, and adjust the transmittance of light, thereby displaying images.
Since liquid crystal molecules display images by changing the transmittance of light according to the direction and intensity of an electric field, LCDs need light for displaying images. Light emitting diodes (“LEDs”), cold cathode fluorescent lamps (“CCFLs”), and flat fluorescent lamps (“FFLs”) have been used as light sources for LCDs.
Conventionally, CCFLs have been used as light sources for LCDs. However, an increasing number of LCDs are using FFLs or LEDs. In particular, LEDs have recently been widely adopted for use in LCDs because of their low power consumption and high luminance.
In general, different LEDs require different forwarding voltages. Therefore, an LED driving circuit must be designed such that the same current can flow into all LEDs. For this, a plurality of LEDs may be connected in series to one another so that the same current can flow into the LEDs.
However, extremely high voltages are generally needed for hundreds of LEDs that are connected in series, and it is difficult to design LED driving circuits capable of generating such high voltages.